TROUBLESHOOTING Service Manual M4 - M10
11.07.2002 Page 56
Connect the oscilloscope to adapter’s exposed leads which represents pins 1 -
2 (1=emitter, 2=gate) of connector X9, while the oscilloscope is in ranges
5V/div, 100us/div sweep time.
When all the connections are done and double-checked, switch ON the
external power supply and carefully raise voltage until nominal operation
voltage level in DC bus is achieved. Minimum voltage to get circuitry up and
running is the level, where internal power supply starts up and under voltage
protection does not block the operation of the logic.
Select control place at panel and enable drive to run at 0Hz. The shape of the
gate pulses shall follow control from logic in time and level shall be in range
(+15V / -12V).
Positive level of the gate signal shall remain within (14,5 - 15,5) V in one bay
units and respectively (14,9 – 15,1) V in units constructed in multiple bays (M8
to M10).
Figure 7.4 Gate pulses
Existence of the negative signal is very important for reliable operation of
IGBT, especially in situations, where IGBT should be able to block down high
collector current to ensure protection from excessive loading (-12V) – (-16V).
Repeat the procedure as above to check signals from other phases, from
terminals X11 (phase V) and X13 (phase U). Sometimes it is needed to
measure same phase simultaneous control pulses between sections (only M8
to M10) to check the timing of control pulses. It should not variate more than
100ns.
7.3.2.4 Checking of voltage measurement circuit
Units in power range CX2 and CXL2 up to 55 kW
CX4 and CXL4 up to 90 kW
CX5 and CXL5 up to 90 kW
CX6 up to 75 kW
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